Mars at perigee

Dominic Ford, Editor
From the Outer Planets feed


Objects: Mars

1990–1991 apparition of Mars

20 Oct 1990 – Mars enters retrograde motion
19 Nov 1990 – Mars at perigee
27 Nov 1990 – Mars at opposition
01 Jan 1991 – Mars ends retrograde motion

Mars's orbit around the Sun will carry it to its closest point to the Earth – its perigee – passing within 0.52 AU of us.

The days around perigee represent the best time to observe Mars, since both its size and brightness in the night sky increase when it is close to us.

This effect is especially dramatic for Mars since it neighbours the Earth in the Solar System, orbiting a little further out from the Sun than us, at an average distance of 1.52 AU. As a result, it has the greatest variation of all the planets in its distance from the Earth, depending on whether the two planets are on opposite sides of the Sun, or passing next to one another in their respective orbits.

Mars reaches perigee at around the time when it passes the Earth in its orbit. At this time, the Sun, Earth and Mars lie in a straight line, with the Earth in the middle.

Consequently, Mars appears almost exactly opposite the Sun in the sky – a configuration called opposition, when Mars reaches its highest point in the sky at midnight and is visible for much of the night.

Every perigee of Mars is associated with a near-simultaneous opposition, but the two events typically occur a few days apart owing to the significant ellipticity of Mars's orbit.

On this occasion, Mars will attain a maximum angular diameter of 18.1 arcsec at closest approach, and a maximum brightness of magnitude -2.0 .

Observing Mars

Even at its closest approach to the Earth, it is never possible to distinguish Mars as more than a star-like point of light with the naked eye, though a simple pair of binoculars is sufficient to reveal it as a disk of light.

From South El Monte , it will be visible in the morning sky, becoming accessible around 18:02, when it reaches an altitude of 7° above your north-eastern horizon. It will then reach its highest point in the sky at 00:25, 78° above your southern horizon. It will be lost to dawn twilight around 06:11, 15° above your western horizon.

A chart of the path of Mars across the sky in 1990 can be found here, and a chart of its rising and setting times here.

The table below lists Mars' angular size and brightness at two-week intervals throughout its apparition:

Date Right ascension Declination Angular size Magnitude
18 Sep 199004h26m40s20°16'N12.5”-0.7
02 Oct 199004h44m30s21°15'N13.9”-1.0
16 Oct 199004h53m10s21°59'N15.4”-1.3
30 Oct 199004h50m10s22°31'N17.0”-1.6
13 Nov 199004h35m20s22°47'N18.0”-1.9
27 Nov 199004h13m00s22°38'N17.9”-2.0
11 Dec 199003h52m40s22°14'N16.7”-1.7
25 Dec 199003h41m30s21°57'N14.7”-1.2
08 Jan 199103h41m30s22°04'N12.7”-0.8
22 Jan 199103h51m10s22°35'N10.9”-0.3
05 Feb 199104h08m30s23°20'N9.5”0.0

As Mars passes perigee, its position will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 04h25m40s 22°46'N Taurus -2.0 18.1"

The coordinates above are given in J2000.0.

The sky on 30 Jan 2026

The sky on 30 January 2026
Sunrise
06:48
Sunset
17:19
Twilight ends
18:46
Twilight begins
05:22


Waxing Gibbous

98%

12 days old

Planets
Rise Culm. Set
Mercury 07:18 12:32 17:45
Venus 07:14 12:28 17:43
Moon 15:01 22:35 06:01
Mars 06:37 11:44 16:50
Jupiter 15:16 22:24 05:33
Saturn 09:12 15:08 21:03
All times shown in PST.

Source

The circumstances of this event were computed using the DE430 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).

This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.

Related news

19 Nov 1990  –  Mars at perigee
27 Nov 1990  –  Mars at opposition
01 Jan 1991  –  Mars ends retrograde motion
28 Nov 1992  –  Mars enters retrograde motion

Image credit

© NASA/Hubble Space Telescope

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